The present invention relates to a sheet for protecting paint films of automobiles., which prevents paint films of automobiles from denaturation and discoloration and thus appropriately protects the surface of bodies or parts of automobiles.
When loading automobiles, the parts thereof, etc., just finished painting on trucks or ships and transporting remote places such as overseas, etc., it has been a practice to coat the automobiles, the parts thereof, etc., with coating material containing wax as the main components to give a thickness of 5 to 40 xcexcm so as to prevent them from being damaged, frosted, discolored, etc., by various floating matters and colliding matters such as dirts, dusts and rainwater. However, this method suffers from some problems, for example, that uniform protection can be hardly achieved thereby due to difficulties in forming a wax coating film of a uniform thickness; that the paint film may be easily stained; that the paint film is liable to be damaged by acid rain; that the wax, etc. would ooze out onto the paint film and thus cause discoloration, etc.; that a large labor is required in forming the paint film; and that use of a solvent and the waste liquid treatment frequently cause environmental problems.
On the other hand, there are known various surface protecting sheets comprising a pressure-sensitive adhesive layer provided on a support. As protecting sheets for painted adherends having films there are proposed ones provided with radiation-cured pressure-sensitive adhesive layers having a lowered glass transition point or polyisobutyrene-based rubber pressure-sensitive adhesive layers in JP-A-2-199184 (The term xe2x80x9cJP-Axe2x80x9d as used herein means an xe2x80x9cunexamined published Japanese patent applicationxe2x80x9d) and JP-A-6-73352. The above-mentioned problems can be solved by using this sheet-like system.
However, the conventional protecting sheets suffer from a problem that when these sheets are peeled off from paint films of automobiles after used, there arise hardly repairable damages such as discoloration and denaturation of the paint films.
To overcome these problems, the present inventors have conducted extensive studies and, as a result, found that the above-mentioned damages occur based on the following mechanism. Namely, rainwater or washing liquor such as window washer penetrates into a gap between a pressure-sensitive layer and a paint film through wrinkles which have been unavoidably formed in adhering a protecting sheet to the paint film of automobiles. The liquid then retains in the air bubbles entrapped in the gap and concentrates therein due to the evaporation of moisture, thus causing the damages such as discoloration and denaturation of the paint film of automobiles.
It is therefore an object of the present invention to provide a sheet for protecting paint films of automobiles, which can prevent the paint film of automobiles from suffering from damages such as discoloration and denaturation even if rainwater or washer penetrates into the gap between the pressure-sensitive layer of the protecting sheet and the paint film while achieving excellent protection function to suspended matters, colliding matters, etc., inherent to protecting sheets and being easily peeled off and removed after completion of the desired protection.
The foregoing object of the present invention will become apparent from the following detailed description and examples.
The present invention provides a sheet for protecting paint films of automobiles, comprising a pressure-sensitive adhesive layer having a roughened surface provided on a substrate made of a fiber sheet.